Investigations will be undertaken to define the molecular defect in the neurovisceral storage disease Fucosidosis. Immunochemical studies (double immunodiffusion, precipitation and inhibition reactions, and radioimmuno-competitive binding assays) will be undertaken using the IgG fraction of anti-alpha-L-fucosidase antibody to determine whether Fucosidosis patients biosynthesize an antigenically similar, but structurally altered, alpha-L-fucosidase. If present, the mutant alpha-L-fucosidase will be purified from tissues (liver and fibroblasts) from patients with Fucosidosis by affinity chromatography, kinetically characterized and compared to the properties of the normal enzyme. Attempts will be made to hydrolyze the fucoglycolipid (which has been isolated from the liver of a Fucosidosis patient) using purified normal liver alpha-L-fucosidase. The carbohydrate composition of homogeneous liver alpha-L-fucosidase will be determined by gas liquid chromatography, amino acid analysis of amino sugars and by several methods for determining sialic acid. The seven isoelectric forms of liver alpha-L-fucosidase will be separated by preparative isoelectric focusing and characterized kinetically and immunochemically. The chemical relationship of the seven isoelectric forms will be investigated using neuraminidase and sialyltransferase.